Seven al-Shabab militants who attacked a high-security prison in Somalia’s capital have all been killed, the country’s government has said.

A huge explosion and gunfire were heard coming from Godka Jilicow – a detention centre that holds al-Shabab militants – in Mogadishu on Saturday evening.

In a statement, al-Shabab said it released “all the Muslim prisoners” from the facility and inflicted heavy casualties on those guarding the centre.

The militants disguised themselves as soldiers in order to enter the prison, government-run news agency Sonna Live reported on Sunday.

The government did not indicate how many of its security forces were killed during the incident, but gave its condolences to the families of “the fallen heroes”.

Likewise, al-Shabab did not give a death toll for its militants.

The fighting began at around 16:40 local time (13:40 GMT).

Godka Jilicow is located near the Somali presidential palace, in the heart of Mogadishu. It is manned by Somalia’s National Intelligence and Security Agency (Nisa) and holds al-Shabab militants and other high-profile detainees.

The attack is a major blow to Nisa and is likely to raise questions about how the militants were able to access one of the most heavily guarded areas in the capital.

Al-Shabab is affiliated to al-Qaeda and has waged a brutal insurgency against the government in Somalia for nearly 20 years.

Hours before Saturday’s attack took place, the government had reopened key roads in Mogadishu which were previously closed for security reasons, citing improvements in the city’s safety.